Insertable power circuit breaker

ABSTRACT

A power circuit breaker includes an insertion rack which is arranged in a distribution unit and a lock system for locking the power circuit breaker in the insertion rack in a locking system. The locking system can be actuated by a drive mechanism, in particular by the switch shaft of the power circuit breaker.

This application is the national phase under 35 U.S.C. § 371 of PCTInternational Application No. PCT/DE2003/002885 which has anInternational filing date of Aug. 28, 2003, which designated the UnitedStates of America and which claims priority on German Patent Applicationnumber DE 102 51 002.4 filed Oct. 30, 2002, the entire contents of whichare hereby incorporated herein by reference.

FIELD OF THE INVENTION

The invention generally relates to a power circuit breaker having awithdrawable-part rack. In one example, it relates to one which can bearranged in a switchgear assembly by use of the withdrawable-part rack.

BACKGROUND OF THE INVENTION

Power circuit breakers of the generic type are known. By arranging themin their withdrawable-part rack, they can be inserted or withdrawn in orfrom a switchgear assembly in a simple manner. In this case, significantimportance is given to locking the power circuit breaker in itswithdrawable-part rack.

In particular in the case of power circuit breakers having a highshort-circuit disconnection capacity, a force occurs, owing to the loopeffect of the current path of the power circuit breaker or of theswitchgear assembly, which acts on the power circuit breaker. This forceis directed such that the power circuit breaker is forced out of itswithdrawable-part rack.

In particular in the case of high flowing currents (short-circuitcurrents), considerable forces acting on the power circuit breaker occursince the force acting rises with the square of the current. If in thiscase the power circuit breaker is not fixed in its withdrawable-partrack precisely in the line of action of this force, the power circuitbreaker may be subjected to a torque owing to leverage. The result isthat the power circuit breaker experiences a tipping movement whichleads to a relative movement between the connection pieces of theswitching contacts of the power circuit breaker and the contactlaminations of the withdrawable-part rack.

This relative movement may lead to a separation of the switchingcontacts from the contact laminations, with the result that arcformation cannot be ruled out. As a result of the high flowing currents,destruction of the power circuit breaker would be associated with this.

It is known to latch the power circuit breaker with itswithdrawable-part rack by way of a latching device. In this case,retaining systems are known which are actuated by an insertion shaft oran insertion drive for the purpose of inserting the power circuitbreaker in the withdrawable-part rack. Such retaining systems, however,are typically of a complex design. Furthermore, a minimum amount of playis provided between the restraining elements of the retaining system andthe withdrawable-part rack, since only a simultaneous movement betweenthe power circuit breaker and the withdrawable-part rack and lifting-outof the restraining systems is possible.

In addition, rigid systems are known, by which the insertion directionor the withdrawal direction of the power circuit breaker in or out ofthe withdrawable-part rack can be blocked. These systems have arelatively small, effective lever arm, such that the high forces whichoccur in particular in the case of a short-circuit cannot reliably beabsorbed.

DE 196 47 747 C1 discloses an insertable device carrier having alatching device. In this case, a latching rod is displaced at the sametime owing to a rotation of an actuating shaft of a main breaker. Thelatching rod in turn displaces a blocking slide. The result is thatlatching of the device carrier takes place.

As a result, single-point latching of the device carrier is achievedsuch that it is positioned. However, if high forces are acting owing tohigh currents flowing (short-circuit currents), the latching rod knownfrom DE 196 47 747 C1 forms a lever arm such that a displacement of thedevice carrier. Accordingly, a power circuit breaker from the desiredlatched position cannot be ruled out. The point of engagement of thelatching rod in a latching opening in a device floor in this case actsas a pivot in order that a deflection of the latching rod can takeplace.

SUMMARY OF THE INVENTION

An embodiment of the invention includes an object of creating a powercircuit breaker which can be latched safely in its withdrawable-partrack by way of a simple arrangement.

According to an embodiment of the invention, an object may be achievedby a power circuit breaker. As a result of the fact that the latchingdevice of the power circuit breaker can be operated by a switchingdrive, in particular by a switching shaft of the power circuit breaker,it is advantageously possible to link the closure of the switchingcontacts of the power circuit breaker with the latching of the powercircuit breaker in the withdrawable-part rack. This operativeconnection, which is thus almost provided, between the closed switchingcontacts of the power circuit breaker and the latching of the powercircuit breaker in the withdrawable-part rack makes it possible to applya restraining force on the power circuit breaker which is matched to theswitching position of the power circuit breaker, and which holds thepower circuit breaker securely in the desired position, even in theevent of high currents flowing.

In particular, a situation is prevented in which the forces injected bythe high currents force the connection pieces of the switching contactsand the contact laminations of the withdrawable-part rack apart from oneanother. The result is that the arc formation mentioned initially can besuppressed.

In one preferred refinement of an embodiment of the invention, provisionis made for the switching shaft to include at least one actuatingelement. This element is connected to the switching shaft such that itis fixed against rotation and by which the latching device can bebrought into the latched position or the unlatched position. As aresult, the actuation of the latching device is possible in aparticularly simple manner.

The switching shaft of the power circuit breaker in this case bears agear or gear segment, which is arranged such that it is fixed againstrotation, preferably outside of an exterior limiting structure. As aresult, it is possible in a particularly simple manner to couple theswitching movement of the contact arrangement to the actuation of thelatching device. The switching shaft undergoes a rotary movement, whichis at the same time used to actuate the latching device, for connection,i.e. for the purpose of closing the switching contacts, or fordisconnection, i.e. for the purpose of opening the switching contacts,of the power circuit breaker.

In particular if, in one further example refinement of an embodiment ofthe invention, the axially displaceable latching bolts have a toothedrod section which meshes with the actuating element. The rotary movementof the switching shaft can easily be converted into a lifting movementof the latching bolts. It is thus possible to lock the power circuitbreaker in a reliable manner.

In accordance with further refinements of embodiments of the invention,the actuating element can be operatively connected to the latching boltvia a crank arrangement, open or closed cam disks, cable pulls, Bowdencables or the like. Irrespective of the specific design of thisoperative connection, the rotary movement of the switching shaft can betransferred in a simple manner to the latching movement or unlatchingmovement of the latching device.

Embodiments include a robust design requiring little or no maintenance.As a result, they are particularly suitable for being used in powercircuit breakers which are subjected to relatively robust operatingconditions.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, features and details of the invention will becomeevident from the description of illustrated example embodiments givenhereinbelow and the accompanying drawings, which are given by way ofillustration only and thus are not limitative of the present invention,wherein:

FIG. 1 shows a schematic view of a power circuit breaker;

FIG. 2 shows a schematic plan view of a first embodiment of a latchingdevice of the power circuit breaker; and

FIG. 3 shows a second embodiment of a latching device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a schematic illustration of a power circuit breaker 10, forreasons of clarity details being omitted from the illustration. Inaccordance with the illustration, the power circuit breaker is, forexample, a three-pole power breaker.

The power circuit breaker 10 includes a switching shaft 12, by whichmovable switching contacts of the power circuit breaker 10 can be guidedtowards fixed switching contacts (closed position) or away from theswitching contacts (open position). For this purpose, the switchingshaft 12 can be rotated about its longitudinal axis in a correspondingangular range by a drive arrangement (not shown).

The power circuit breaker 10 can be arranged in a switchgear assembly(not shown) by way of a withdrawable-part rack 14 which is merelyindicated.

The switching shaft 12 is extended beyond lateral structural elements16, for example retaining and accommodating frames, and bears there, onboth sides, a latching device which is given the overall designation 18.The design and operation of the latching device 18 will be explained inmore detail with reference to FIG. 2.

The latching device 18 includes an actuating element 20, which isarranged such that it is fixed against rotation on the switching shaft12 and which interacts with a latching bolt 22. The latching bolt 22 isarranged such that it can be displaced axially and is guided, forexample by means of guide rollers 24.

The actuating element 20 is formed by a gear segment 26, which has anassociated toothed rod section 28 of the latching bolt 22. The gearsegment 26 and toothed rod section 28 are in meshing engagement witheach other.

The latching device 18 illustrated in FIGS. 1 and 2 has the followingoperation:

When the switching shaft 12 is actuated for the purpose of closing theswitching contacts of the power circuit breaker 10, the switching shaftis rotated about its axis of rotation 30, as shown in the illustrationin FIG. 2 in the counterclockwise direction. As a result, the actuatingelement 20, which is connected to the switching shaft 12 such that it isfixed against rotation, experiences an identical rotary movement. As aresult of the fact that the actuating element 20 meshes with thelatching bolt 22, the latching bolt 22 experiences a lifting movementwhich is directed in the direction of the arrow 32.

As a result, the latching bolt 22 engages in a corresponding opening 34in the withdrawable-part rack 14. For the purpose of inserting thelatching bolt 22 precisely in the opening 34, the latching bolt 22 mayhave a conical tip 35.

It becomes apparent that the switching movement of the power circuitbreaker 10 may be transferred in a simple manner to the actuation of thelatching device 18 via the switching shaft 12. Thus, when the powercircuit breaker 10 is connected, the latching device 18 may beautomatically moved over into the latched position. The power circuitbreaker 10 is thus in any case secure during its connected state.

In this case, a controlled movement of the latching device 18 takesplace such that it is already latched before primary arcing contact ofthe power circuit breaker 10 is effective. This ensures that the lockinghas already reliably taken place even in this connected state of thepower circuit breaker 10.

Unlatching of the latching device 18 takes place in analogous fashion byopening the power circuit breaker 10. In this case, in turn theswitching shaft 12 experiences an opposite rotary movement about theaxis of rotation 30, in accordance with the illustration in FIG. 2), inthe clockwise direction. The correspondingly resulting rotary movementof the actuating element 20 is transferred to the latching bolt 22, withthe result that the latching bolt 22 is lowered in opposition to thelifting movement 32, with the result that the latching bolt 22 is movedout of engagement with the opening 34.

As indicated in FIG. 2, the actuating element 20 has associated with ita further latching bolt 22′ which is arranged diametrically opposite thelatching bolt 22. The design and operation of the latching bolt 22′corresponds to those of the latching bolt 22. Owing to the diametricallyopposite arrangement, in the case of a lifting movement 32 of thelatching bolt 22, the latching bolt 22′ experiences a lifting movement32′ in the opposite direction. This makes it possible at the same timeto latch the power circuit breaker 10 both in an upper section and in alower section of the withdrawable-part rack 14.

In the case of two latching devices 18 being provided, there is thus atotal of four latching points. These latching points ensure securepositioning of the power circuit breaker 10 in its withdrawable-partrack which takes place even in the event of high currents and which isresistant to the action of high forces. Relative movements of connectionpieces (not illustrated in any more detail) of the switching contactsand contact laminations of the withdrawable-part rack in relation to oneanother can thus be prevented.

FIG. 3 shows a modified embodiment of the latching device 18. In thiscase, FIG. 3 a shows the unlatched position, and FIG. 3 b shows thelatched position. Identical parts to those in the preceding figures areprovided with identical reference numerals and will not be explainedagain.

In contrast to the exemplary embodiment shown in FIGS. 1 and 2, theactuating element 20 is in this case in the form of a crank arrangement36, which interacts with a corresponding link guide 38 of the latchingbolts 22 and 22′, respectively. This also makes it possible, in a simplemanner, for the rotary movement of the switching shaft 12 to beconverted into the lifting movement 32 of the latching bolts 22 and 22′.

The actuating element 20 has associated with it two diametricallyopposite latching bolts 22 and 22′, respectively. Here too, an actuatingelement 20, in the form of a twin-crank arrangement, interacts with linkguides 38 of the in this case two latching bolts 22 and 22′.

Exemplary embodiments being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

1. A power breaker having a withdrawable-part rack which can be arrangedin a switchgear assembly and having a latching device for the purpose oflatching the power breaker in the withdrawable-part rack in a latchedposition, it being possible for the latching device to be actuated by adrive arrangement, in particular by a switching shaft of the powerbreaker, characterized in that the latching device (18) comprises twolatching bolts, which can be displaced essentially axially in opposingdirections of action and which can be brought into interlockingconnection with the withdrawable-part rack.
 2. The power breaker asclaimed in claim 1, characterized in that the latching device (18)comprises at least one actuating element (20), which is connected to theswitching shaft such that it is fixed against rotation and by means ofwhich the latching device (18) can be brought into the latched positionor into the unlatched position.
 3. The power breaker as claimed in claim2, characterized in that the actuating element (20) is a gear or a gearsegment (26) which meshes with a toothed rod section (28) of thelatching bolts (22, 22′).
 4. The power breaker as claimed in claim 2,characterized in that the actuating element (20) is a crank arrangement(36), which is in engagement with a link guide (38) of the latchingbolts (22, 22′).
 5. The power breaker as claimed in claim 2,characterized in that the actuating element (20) is connected to thelatching bolt (22, 22′) via open or closed cam disks.
 6. The powerbreaker as claimed in claim 2, characterized in that the actuatingelement (20) is connected to the latching bolts (22, 22′) by means of acable pull, a Bowden cable or the like.
 7. The power breaker as claimedin one of the preceding claims, characterized in that the latchedposition of the latching device (18) is reached before primary arcingcontact of the power breaker (10) is effective.